Ta có: \(3^n.15^2=3^n.3^2.5^2=3^{n+2}.5^2\)
Ta có: ( n + 2 + 1)((2 + 1) = 15
( n + 3) . 3 = 15
n + 3 = 5
n = 2
Vậy n = 2
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tim so tu nhien n sao cho so 3^n . 15^2 co tat cac 15 uoc
tim so tu nhien n sao cho 3^n.6^2 co 15 uoc .ket qua n=
so tu nhien n sao cho 3n . 15 co 15 uoc so
Tim cac so tu nhien n sao cho :
A. n+1 la uoc cua 15
B. n+5 la uoc cua 12
tim so tu nhien a biet a=2^x.3^y voi x y thuoc N* va a co 15 uoc
tim so tu nhien n chi co 2 thua so nguyen to biet rang n^2 co 21 uoc so hoi n^3 co bao nhieu uoc so
tim so tu nhien nho nhat co:
+ 9 uoc
+ 15 uoc
bai 1:tim n thuoc n de:3(n+2) chia het cho n-2bai 2chng minh rang cac so sau la cac so nguyen to cung nhaua) 18n+3 va 21n+4b)2n+1va3n+1bai 3:tim hai so biet tong hai so la 90 va uoc chung lon nhat la 15bai 4:tim so tu nhien n lon nhat co 3 chu so sao cho n :15 du 9va n:35 du 29bai 5:tim uoc chung lon nhat cua cac so sau:a)18n+3 va 21n+4b)9n+13 va 3n+4bai 6:chung minh: voi moi a,b thuoc nta coUCLN(a,b)UCLN (5a+2b,7a+3b)AI DUNG TRUOC 9H MINH SE TICH CHO.THANHK YOU VERY MUCH!
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bai 1:tim n thuoc n de:3(n+2) chia het cho n-2
bai 2chng minh rang cac so sau la cac so nguyen to cung nhau
a) 18n+3 va 21n+4
b)2n+1va3n+1
bai 3:tim hai so biet tong hai so la 90 va uoc chung lon nhat la 15
bai 4:tim so tu nhien n lon nhat co 3 chu so sao cho n :15 du 9va n:35 du 29
bai 5:tim uoc chung lon nhat cua cac so sau:
a)18n+3 va 21n+4
b)9n+13 va 3n+4
bai 6:chung minh: voi moi a,b thuoc nta co
UCLN(a,b)=UCLN (5a+2b,7a+3b)
AI DUNG TRUOC 9H MINH SE TICH CHO.THANHK YOU VERY MUCH!
1 tim so tu nhien n sao cho
a N + 1 la uoc cua 20
b N + 3 la uoc cua 15
c 10 chia het ( x - 2 )
d 12 chia het ( 2x + 1 )